## Precalculus: Mathematics for Calculus, 7th Edition

$18y^{3}x^{2}-2xy^{4}=2yx^{3}(9x-y)$.
Can begin by factoring out a factor of 2 hence $18y^{3}x^{2}-2xy^{4}=2(9y^{3}x^{2}-xy^{4})$. Can also factor out a factor of $y^3$ hence $2(9y^{3}x^{2}-xy^{4})=2y^{3}(9x^{2}-xy)$. Can then also factor out an $x$ hence $2y^{3}(9x^{2}-xy)=2yx^{3}(9x-y)$. The original expression is now fully factorized.